1. Field of the Invention
The present invention relates generally to navigation systems and, in particular to an acoustic underwater diver navigation system which may be used by a diver to locate submerged objects.
2. Background of the Invention
Underwater diver operations for many purposes can be hampered by the lack of visibility due to the turbidity or depth of water the diver finds himself. This is especially true if the diver is attempting to locate submerged objects which are located at a considerable distance away from his current position and cannot be seen. With zero or near zero visibility, a diver also can become confused and disorientated so that he does not know north, south or other directions.
One striking example of the problems encountered by a diver under such circumstances is when he is attempting to inspect and when required repair existing sea floor equipment such as moorings, cables, cable protection systems and outfalls. In addition, the lack of visibility that an underwater diver often finds himself in may hamper attempts to install new underwater equipment, as well as inspect and repair waterfront and near shore facilities.
In the past, one widely used technique for locating an object underwater has been to provide the diver with a search line of predetermined length, for example one hundred feet, that is connected to a weight or other structure at a particular sea floor location near the object the diver is attempting to locate. The diver, who is usually weighted down, then walks in a circle while holding the line taut, after which another section of line may be added and a circle walked in the opposite direction. This circular procedure is repeated until the object is located either by a visual sighting by the diver or by snagging the taut line.
However, since a sea floor area to be surveyed may encompass an area of a circle over 2000 feet in radius from the center point of the circle, it is apparent that a diver must expend a great deal of time and energy in overlapping small circles. This is especially critical when a diver is working at approximately 300 feet or more and the bottom time is limited to thirty minutes. The diver must then be brought to the surface in a controlled manner to avoid getting decompression sickness before diving again at some time latter. Such interruption substantially increase the time required for installation of new underwater equipment or inspection and when required repairs of existing underwater equipment.
Moreover, if the sea bottom is relatively soft or is overlaid by layers of silt, a diver often finds himself knee-deep in sand or mud while walking which can be physically exhausting. Bottom holes, depressions or other geographical features which cannot be seen by the diver also pose danger if he unexpectedly encounters them.
Another current search technique is to place a sonar transmitter/receiver transducer on the sea floor so that sonic waves reflected from the diver and other underwater objects are shown as echo images on a shipboard or other remote station monitor. Based on the location of these monitored images which represent the diver and objects to be inspected or repaired, a remote station operator then gives audio commands to the underwater diver via telephone cable in an effort to guide or direct his movements to these objects. However, such remote audio guidance has not proven to be particularly efficient either in time or effort because of directional disorientation experienced by the diver due to lack of visibility.
With these and other disadvantages known to prior art underwater diver navigation systems the present invention was conceived and one of its objects is to provide a relatively simple, yet highly efficient diver navigation system to provide visual aids to a diver for quickly and safely enabling the diver to locate submerged objects for inspection and when required repair.
It is a further object of the present invention to provide a reliable diver navigation system which may be used to map and provide fixed coordinates for the installation of new underwater equipment.
It is a yet a further object of the present invention to provide a synchronous range-range diver navigation system operating on a repeating timing cycle and which indicates to the user whether he is heading in the proper direction to traverse a predetermined course to locate the underwater object to be inspected.
Various other advantages and objectives of the present invention will become apparent to those skilled in the art as a more detailed description of the present invention is set forth below.